The "box" was of course the wing spar. TCA remarkably had a stewardess on the even smaller Lockheed 10A Electra. The 10A also had a wing spar to step over, but the spar step-over was located just aft of the cockpit bulkhead. Canadian Pacific Airlines (CPA, later known as CP Air) also operated a few Lockheed 14-H2 Super Electra aircraft in the 1940's. They also employed a stewardess on every flight.
A CPA Lodestar on a snow covered apron somewhere in western Canada:
https://i.imgur.com/NZWT0vf.jpg